Miniaturized Plant for Producing Gas Mixtures

ABSTRACT

The invention relates to a plant for filling gas cylinders with pure gases and/or mixtures of pure gases or special gases, said plant including: a device for selecting gas and/or for making mixtures of gases to be fed into a gas cylinder; apparatuses for analyzing the composition of said mixtures or said pure gases; characterized in that the following measures are implemented: the plant is integrally contained in a transportable container having a ground surface lower than 45 m 2 , said ground surface preferably being between 34 m 2  and 40 m 2 ; the devices contained in said container are attached to the walls of the container and can be connected to gas sources outside the container; the arrangement thus obtained enables the users to access said devices and apparatuses from the inside of said container and to fill the cylinders inside said container.

The present invention relates to plants for filling cylinders with pureindustrial gases or mixtures of pure gases or of special gases.

The gases involved in such filling operations are, for example:

-   -   those taken from the air (N₂, Ar, O₂), helium, hydrogen and        mixtures thereof in concentrations typically at the percent        level with other gases, when the cylinders are filled in        “batches” (several cylinders at a time).    -   carbon dioxide or nitrous oxide, the cylinders of which are        filled by weighing, one cylinder at a time.

The mixtures of special gases are mixtures of compressed or liquefiedgases in cylinders, which mixtures are notably characterized by thefollowing aspects:

-   -   great accuracy regarding the concentration of the constituents;    -   a great many constituents, sometimes several tens of        constituents, such as, for example, the hydrocarbon mixtures        used in refinery and the petrochemical industry;    -   the difficulty in maintaining the stability of the concentration        of the constituents when these are reactive toward the walls of        the cylinder especially if their concentration is low.

These are therefore mixtures which are very accurate in terms of thecompositions and/or which contain very low contents of compositions,these contents being at the ppm level.

These characteristics entail complex production equipment in order,notably:

-   -   to clear and passivate the inside of the cylinders that are to        be filled, so as to obtain concentrations of constituents that        are reactive toward the walls of the cylinders which remain        stable over time;    -   to produce mixtures with a high degree of accuracy regarding the        concentration of the constituents;    -   to control the composition of the mixtures.

Incorporating such equipment into a production plant requires specialistdesign studies and suitable buildings (for example buildings withcontrolled temperature). The lead times involved in the design phase andthe cost of appropriate buildings are great. In particular, the costsare too high if the market is too small or sometimes difficult tojustify because of a risky economic environment and a little-knownmarket or an unstable economic climate.

Moreover, it has been found that the sophistication of plants isevolving rapidly. The industrial world is increasingly switching overfrom so-called heavy industry to units producing consumer products andgoods. This is leading first to a change in the size of plants andsecond to a call for increasingly sophisticated very differentproduction machinery originating from highly varied geographiclocations.

Whether a plant is to be big or small, simple or complex, the approachfollowed when building such a plant has remained conventionally thesame. “Turnkey” solutions are very often employed. These have theadvantage to industry of forcing the supplier or suppliers to complywith a preset technical and financial objective and thus guaranteeindustry (the end user customer) results. In consequence, the productionof a plant as a “turnkey” solution is organized as follows:

First of all, the production machinery is built at various existingplants, for example in already-developed countries.

These various machines are sent over land or by sea to the final site.

These machines are set up in a traditional or prefabricated buildingthat has already been erected on the final site.

The machines are set up and connected together (fluid, electricity, pipework, etc.) inside the building on the final site.

The machines are tested on the final site prior to start-up.

This conventional method involving distant turnkey industrial units, forexample situated in developing countries, does have a good number ofuncontrollable factors associated with it. All that is needed is for theordered equipment to arrive when the erection of the building on thefinal site has been delayed and there is a risk that this equipment willremain in crates for several months or even more. This leads todegradation of the machinery and requires expensive reconditioning.

Problems arise just as frequently if the machines are not all deliveredwithin the agreed deadline. A missing element in the middle of the linecan prevent a plant or a part of a plant from being started up in itsentirety.

With this conventional turnkey plant solution, several partnersgenerally share in the project at various stages and at locations whichare geographically remote from one another. The production plantappoints equipment specialists to supervise the setting-up, start-up andfinal acceptance phases. The design and production engineering concernappoints specialist engineers for the detailed design, set-up drawingsand testing. This results in numerous communication problems. This isparticularly the case when the industrial end user or a local companyhas adopted responsibility for erecting the building and installing theequipment.

By transferring the plants around it is possible to reduce theproduction costs and more effectively amortise the investments for newindustrial entities. However, the current situation is essentiallyrestricted to providing the option of transporting the various machines,respective internal receptacles of the type used generally for goodsthat can be moved around by sea or by road (using trucks). That does notreduce the times and costs below certain limits because the machineshave to be loaded into the receptacles and removed therefrom and thenthe production line has to be reassembled.

One technical problem addressed by the present invention is thereforethat of providing a plant for the industrial production of mixtures ofpure gases or of special gases, which plant can be dismantled,transported and reassembled simply and quickly.

As will be seen in greater detail in what follows, the plant proposed bythe invention is notable in that, in order to achieve such flexibility:

-   -   the plant is a “miniature” plant such as can be contained in a        container of very small size and nonetheless, given the gases        being handled, it needs to offer first-rate temperature,        accuracy and safety conditions,    -   the plant is operational: in other words, the operators need to        be able to enter it, work in it, move around in it and perform        handling operations, doing all of this inside the plant and in a        space which is nonetheless restricted in order to limit the        movements of the cylinders,    -   for that, the essential equipment that makes up the plant is        secured to a wall of the container, so as to allow the operators        to be able to move around inside the plant while carrying out        all the necessary operations, including the moving-around of the        cylinders,    -   the plant preferably comprises a ventilation system which on the        one hand provides control over the temperature inside the        container, this being so as to allow work to take place inside        the container irrespective of the temperature outside but also        so as to allow accurate mixtures to be created by measuring the        pressure-temperature of the components of the mixtures, and the        ventilation system also allowing any accidental leaks of toxic        and/or flammable gases to be diluted in the internal atmosphere        of the container so that there are no damaging consequences.

Included among the essential equipment that makes up the plant and thatis secured to a wall of the container there are, in particular, items ofapparatus for the vacuum drying of the cylinders prior to first filling,for removing residual gases from the cylinders before they are refilled,for producing mixtures, for purifying gases, and analyzers, etc.

It may be noted that the prior art contains documents such as documentsEP-366 559 and WO 2006/123373 which describe containers that can betransported by sea or by land and contain machinery intended to be usedin a plant; said containers, once combined with one another in anarrangement that is to be defined, form a true plant.

Thus, by way of illustration, WO 2006/123373 relates to an arrangementof containers containing apparatus needed for the intended productionmethod (it is aimed first and foremost at the manufacture of insulatingpanels even though it cites other possible applications such as the“packaging of liquid products”, without anywhere describing the specialcase of the production of gaseous mixtures and its filling intocylinders. However, and above all, it does not describe a plant that theoperators can enter, and in which they can move around, produce aproduct, move the cylinders around in a miniaturized space because quiteclearly the author anticipates the presence of empty containers“adjacent” to the plant allowing operators access to “the productionplant” and quite logically the walls of these containers are then openand in communication. It can therefore be clearly seen from the abovethat WO 2006/123373 is concerned with a quite different type of plantand quite logically WO 2006/123373 is not facing the same set ofproblems and therefore is not in any way proposing a solution thattechnically addresses the problems now presented.

One subject of the present invention is therefore a plant for fillingcylinders with gas using pure gases and/or mixtures of pure gases or ofspecial gases, comprising:

-   -   equipment for selecting gases and/or for producing mixtures of        gases intended to be introduced into a gas cylinder,    -   apparatus for analyzing the composition of said mixtures or of        said pure gases;        characterized by the use of the following measures:    -   the plant is wholly contained in a transportable container, the        footprint of which is less than 45 m2, and preferably the        footprint ranges between 34 m² and 40 m²;    -   the equipment and apparatus contained in said container is        attached to the walls of the container and able to be connected        to gas sources situated outside the container;        the arrangement thus produced allowing the personnel using it to        access this equipment and apparatus from inside said container        and proceed with said filling of the cylinders inside said        container.

Moreover, the plant according to the invention may adopt one or more ofthe following features:

-   -   the plant comprises two parts,        -   i) a first part comprising:    -   equipment for producing mixtures of pure gases or of special        gases intended to be introduced into a gas cylinder,    -   apparatus for analyzing the composition of said mixtures of        special gases or pure gases,        -   j) the other part (3) comprising:    -   at least one emptying means for emptying out residual gases        contained in the cylinders that are to be filled,    -   at least one means of cleaning and/or of passivating the        cylinders that are to be filled,    -   at least one means for homogenizing the produced mixtures.        -   In substance, the plant may then be made up of a single            container containing the two parts in question or            alternatively of two containers placed end to end, and            communicating, there being one container for each of the two            parts involved.    -   the two parts are separated from one another by a movable wall.    -   said first part further comprises a means of controlling the        interior temperature.    -   the equipment for producing mixtures comprises at least one        mixer associated with at least one analyzer.        -   the equipment for producing mixtures comprises:            -   a weighing apparatus and/or manometric apparatus each                able to measure accurately the quantities of gas to be                introduced into the cylinder,            -   a means of connection between the cylinder that is to be                filled and gas sources situated, preferably, outside the                container.        -   the equipment for producing mixtures comprises at least one            line set able to produce any type of compressed or liquid            gas mixtures.        -   the weighing apparatus situated in the container is            positioned on a support independent of the container and the            base of which is situated below the container floor level.        -   the plant comprises at least one apparatus for analyzing the            composition of the mixture, chosen from:            -   at least one gas chromatograph intended to separate the                various constituents of a mixture;            -   at least one thermal conductivity detector (TCD) or                flame ionization detector (FID);            -   at least one oxygen analyzer;            -   at least one moisture analyzer;            -   at least one infrared spectrometer for determining the                concentration of certain compounds in a mixture.

As will have been understood from reading about the sizings preferred bythe invention, preference is given to ISO containers and it will berecalled that:

-   -   a 20-foot ISO container measures 6 m×2.4 m=14.4 m²    -   a 40-foot ISO container measures 12 m×2.4 m=28.8 m²

According to preferred implementations of the invention, the plantcomprises a single 40-foot ISO container or, alternatively, 2 ISOcontainers:

-   -   one 20-foot ISO container for the internal preparation of the        cylinders, and    -   a 40-foot ISO container for producing and analyzing the        mixtures.

As was mentioned earlier on in the present description, the plantpreferably comprises a ventilation system which on the one hand providescontrol over the temperature inside the container, this being so as toallow work to take place inside the container irrespective of thetemperature outside but also so as to allow accurate mixtures to becreated by measuring the pressure-temperature of the components of themixtures, and the ventilation system also allowing any accidental leaksof toxic and/or flammable gases to be diluted in the internal atmosphereof the container so that there are no damaging consequences.

It will have been understood that this system is especially welljustified for the handling of flammable gases (such as H₂ . . . . ) ortoxic gases (such as CO, H₂S, NO₂ . . . ). Further, the objective of itspresence is therefore to avoid the build-up of such gases inside thecontainer.

Such a build-up could of course result only from an accidental leakbecause, as will have been appreciated, in such plants that handle toxicand/or flammable gases, every step is also taken to limit such risks(vents that vent to the outside, filters, collective valves, use ofhigh-pressure equipment, use of corrosion-resistant materials, etc.,which measures are well known to those skilled in the art).

Depending on the gases handled it is possible of course to conceive ofnumerous configurations and positioning of the extraction points,particularly whether these are in a low position and/or in a highposition in order to collect gases that are heavier and also those thatare lighter than air.

Detection of the presence of a toxic or flammable gas, for example bydetectors located inside the vents that discharge to the outside of thecontainer, will lead to chosen actions including: an increase in the airrenewal flow rate, visible or audible alarms, the cutting-off of theelectrical power supplied to most of the container equipment with theexception of the forced ventilation equipment and emergency lighting,etc.

According to one of the embodiments of the invention, the plantcomprises two parts:

-   -   i) a first part housing the equipment for producing the mixtures        and the apparatus for analyzing the composition of the mixtures,        and    -   j) a second part that can be termed the “cylinder preparation”        part housing the equipment for emptying out the residual gases        contained in the cylinders that are to be filled, means for        cleaning and/or passivating the bottles that are to be filled,        means for homogenizing the produced mixtures,        and the plant also comprises a ventilation system comprising:    -   in the “cylinder preparation” 2nd part, two independent forced        ventilation blowers, one for ventilating the entirety of this        2nd part, the other ventilation blower situated specifically        above the location of the cylinders which are in the emptying        phase;    -   and in the “mixture production” 1st part, two independent forced        ventilation blowers, one to ventilate the entirety of this 1st        part and the other ventilation blower situated specifically        above each station at which a cylinder is in the process of        being filled or analyzed.

Another subject of the invention is a method of preparing a mixture ofspecial gases in a cylinder implementing a plant as defined hereinaboveconnected to at least two sources of special gases external to theplant.

According to one of the embodiments of the method of the invention, thecylinder that is to be filled is connected to just one gas source at atime.

According to one of the embodiments of the method of the invention, itcomprises the steps:

-   -   of preparing the cylinder that is to be filled;    -   of filling said cylinder by connecting it to a source of gas,        using a weighing apparatus and/or manometric apparatus each able        to measure accurately the quantities of gas to be introduced        into said cylinder;    -   of analyzing the composition of the content of the cylinder thus        filled.

The container used may be an ISO container that can be transported, forexample, by land and by sea. Thus it is possible to standardize themanufacture of the complete plant at a factory in order to optimizeproduction costs, and to withdraw the container/plant if necessary andtransport it to a more suitable location in order to recoup theinvestment.

Contrary to the prior art documents cited hereinabove, the equipmentcontained in the container is attached to the walls of the container.Specifically, the components such as, for example, the productionequipment or the analysis apparatus is fixed to the walls of thecontainer containing the plant according to the invention. As alreadyexplained hereinabove, on the one hand such an arrangement allows theusers to access this equipment from inside the container while at thesame time allowing this equipment to be connected together and, on theother hand, to gas sources situated outside the container, using pipingattached to the walls of the container. This affords a certain spacesaving and therefore allows the plant to be better miniaturized, butalso ensures better stability of measurements thanks to the securing ofthe apparatus.

By way of illustration, the plant may be placed inside an ISO containermeasuring 12 meters long, 3 meters wide and high, or alternatively twoISO containers measuring 6 meters long positioned end to end.

It should be noted that, according to the prior art, both in terms ofthe filling of pure gases and of the filling of mixtures of pure orspecial gases, the quantity of gas to be filled and the quantities ofraw materials needed mean that a large-sized building housing thefilling plant has always hitherto been considered.

Other specifics and advantages will become apparent from reading thefollowing description which is given with reference to the figures inwhich:

FIG. 1 is a diagram of one example of how a plant according to theinvention is organized;

FIG. 2 is a diagram of equipment for producing mixtures of special gasesincluded in a plant according to the invention.

FIG. 1 depicts a plant 1 according to the invention for producingmixtures of special gases, comprising two parts 2 and 3. The two partsare separated by a movable wall 20. For example, the movable wall 20 isa sliding door. FIG. 1 illustrates the case of an embodiment in a singlecontainer divided into two parts connected by a movable wall, but it isequally possible according to the invention to conceive of an embodimentin which the two parts consist of two ISO containers joined together.

The first “mixture production” part 2 has an interior temperaturecontrolled by a temperature control means. For example, such a means isa heating or an air conditioning system.

Said part 2 houses the equipment 4 used for producing the mixtures andthe apparatus used for analyzing the composition of the mixtures heresituated in zone 5.

One example of equipment 4 for producing said mixtures is depicted inFIG. 2.

Accurate measurement, for example using manometry, of the quantities ofgases to be mixed is preferably carried out using equipment andcylinders for filling in a temperature-controlled space. This controlledtemperature aspect is an essential feature in obtaining appreciablereliability and accuracy on an industrial scale. Temperature control isneeded for the production of accurate mixtures using a barometricmethod.

The “cylinder preparation” part 3 comprises at least one means 6 ofemptying out the residual gases contained in the cylinders that are tobe filled, at least a means 8 of cleaning and/or passivating thecylinders that are to be filled, and at least one means 9 ofhomogenizing the produced mixtures. The plant 1 is wholly contained in atransportable container 10 the footprint of which measures less than 45m², the footprint preferably ranging between 34 m² and 40 m². The heightof the container 10 is, for example, between 2.5 meters and 3.5 meters,and the height is preferably 3 meters.

In practice, personnel enter the container via a door 11 and proceedwith filling the cylinders 7 situated initially in the part 3 andintended for the preparation (cleaning, passivation, emptying) of thecylinders 7. Said filling of the mixtures is performed in part 2, thetemperature of which is controlled, using the mixture productionequipment 4.

The cylinder 7 intended to be filled with a mixture of special gases isfirst of all prepared, if necessary, for example by cleaning using thecleaning and/or passivating means 8, and/or by emptying out the residualgases from the cylinder if this cylinder has already been used, using anemptying means 6.

If it has already been used, said cylinder will therefore probably becontaminated with residual gases. The passivation means 8 is, forexample, an oven into which the cylinder 7 is introduced for a fewhours. Once the cylinder 7 is ready, the user takes possession of itthen rolls or alternatively carries it to the temperature-controlledpart 2 of the plant. The user can then proceed with filling the mixtureof special gases into the cylinder 7 thus prepared. When severalcylinders are ready, the user can transport several at a time in orderto optimize his work time and productivity and stow said cylinders at adedicated location 11.

The mixture production equipment 4 is depicted schematically in FIG. 2.The cylinders intended to be filled are each connected to one and thesame filling line set 12 by connection means 14. This filling line set12 is connected to a control panel 13, for example a CLP. This fillingline set 12 is connected to automatic valves 22 which are connected tomeasurement instruments, for example to the weight measurementformulated by the weighing system 17 so that when the weight of gas tobe introduced into the cylinder is reached, the valve closesautomatically.

The filling line set 12 is also connected to a network 15 of sources ofspecial gases which is located outside the container 10 in which theplant according to the invention is located, as depicted in FIG. 1.According to one of the embodiments of the invention which is of specialbenefit in terms of safety, when a cylinder is in the process of beingfilled, this cylinder is connected to just one single gas source at atime. This is because it is preferable, in order to avoid an explosion,for a source of flammable gas not to be connected at the same time as asource of oxidizing gas to said cylinder while it is in the process ofbeing filled. The fact that the filling line set 12 is able to fill thecylinders with any family of mixtures may entail a cleaning of said lineset 12, particularly a cleaning of the connection volume. Such a lineset 12 may be a single line set according to one embodiment of theinvention. The same line set 12 is able to fill the cylinders withmixtures such as, for example, mixtures of flammable gases/inert gases,oxidizing gases/inert gases, oxidants/fuels. A safety system (notdepicted) that prevents the production of mixtures of incompatible gasesin the equipment may also be added to the container 10.

The quantities of special gases that make up the mixture are measuredand checked using measurement and checking means such as a manometer 16and a weighing system 17. Depending on the degree of accuracy desiredfor the production of the desired mixture, the equipment 4 compriseseither a manometer 16 and a weighing system 17, or just one of thesetwo. Said mixture producing equipment 4 is situated in thetemperature-controlled part 2 of the container 10 and so the stabletemperature allows the pressure to be measured reliably.

In order to avoid measurements being perturbed for example as a resultof vibrations on the floor of the container 10, the weighing system 17here is arranged on a support 18 independent of said container 10. Thebase of the support 18 is situated below the container 10 floor level.For example, this base of the support 18 of the system 17 rests on achassis welded to the container 10 independently of the chassis carryingthe floor of the container 10, so as to limit as far as possible anyvibrations incurred by, for example, people or bottles moving around.

Once the mixture has been created, it is analyzed using analysisapparatus situated in zone 5 of the container 10. The analysis apparatusis, for example:

-   -   gas chromatographs intended to separate the various constituents        in a mixture. The concentration of the constituents in the        mixtures is measured by means of detectors which vary according        to the type of constituent and the concentration thereof. The        detectors most commonly used are thermal conductivity detectors        (TCD) or flame ionization detectors (FID) in the case of        hydrocarbon compounds;    -   oxygen analyzers;    -   moisture analyzers;    -   infrared spectrometers for determining the concentration of        certain compounds in a mixture.

It is good to note that the layout of the components in the plantaccording to the invention is such that the user moves around as littleas possible. The cylinders do not therefore have to be moved very much.Further, the space between the production equipment 4 and the analysisapparatus is large enough that the user can move around but small enoughfor the plant to be miniaturized as far as possible thus limiting themovements of cylinders.

Moreover, such a plant requires only a very low number of personnel torun it. By comparison with real-size plants in existence at the presenttime, the number of individuals working on the plant 1 according to theinvention is very small and the distance required for the transportationof cylinders during the mixture filling process is reduced to theminimum.

When analysis is complete, the cylinders filled with mixtures of specialgases are transported to part 3 of the container 10 to what is known asa homogenizing means 9. Said means 9 is, for example, a cylinder roller.

It is possible that a mixture of gases at the end of the filling of acylinder will not have a homogenous composition throughout the cylinderwhen, for example, the cylinder is filled in a vertical position andwhen the constituent introduced last is of a lower density than theprevious constituents. One way of homogenizing the mixture is to placethe cylinder in a horizontal position and to revolve it about its axisat a speed of several revolutions per minute for a minimum of tenminutes or so.

The means 6, 8 and 9 are automated.

When this operation is complete, the user takes the cylinder filled withthe desired gas mixture out of the container 10 and sets it down at astorage site 19 whence a batch of cylinders will be transported to thecustomer. The storage site 19 is, for example, situated outside thecontainer 10.

One embodiment of the plant 1 according to the invention may berestricted to the manufacture of just a few cylinders of mixtures perday, for example 8 cylinders per eight-hour working day or theequivalent of 2000 cylinders per year, considering mixtures containingthree compounds on average. This type of plant is therefore capable ofsupplying a market corresponding to the needs of several refineriesand/or petrochemical industries and/or car plants.

As has been stated, FIG. 1 illustrates the situation in which the plantcomprises two parts:

-   -   i) a first part 2 housing the equipment used to produce the        mixtures and the apparatus used for analyzing the composition of        the mixtures, and    -   j) a second part 3 housing the equipment that could be termed        “cylinder preparation” equipment notably including means of        emptying out residual gases contained in the cylinders that are        to be filled, means of cleaning and/or passivating the cylinders        that are to be filled, means of homogenizing the mixtures        produced,        and according to one of the embodiments of the invention, the        plant also comprises a ventilation system comprising:    -   in the “cylinder preparation” part 3, two independent forced        ventilation blowers, one for ventilating the entirety of this        2nd part 3, and the other ventilation blower situated        specifically above the site of the cylinders in the emptying        phase.

By way of illustration and to give a better feel for the invention,practical examples of flow rates are given here, with:

-   -   for the ventilation of the entirety of the “cylinder        preparation” part 3, an air flow rate in normal operation of 150        Nm³/h corresponding to 5 renewals per hour, and of 800 Nm³/h if        a toxic or flammable leak is detected.    -   for the ventilation above the cylinders being emptied, under        normal operating conditions a ventilation flow rate of 100 Nm³/h        for each cylinder is applied with, on the whole, 1200 Nm³/h if a        toxic or flammable leak is detected.    -   in the “mixture production” part 2, there are two independent        forced ventilation blowers, one for ventilating the entirety of        this 1st part 2, the other ventilation blower being situated        specifically above each station at which a cylinder is in the        filling or analysis phase.

By way of illustration and to give a better feel for the invention,practical examples of flow rates are given here, with:

-   -   for the ventilation of the entirety of the “mixture production”        part 2, an air flow rate in normal operation of 300 Nm³/h        corresponding to 5 renewals per hour, and of 1200 Nm³/h if a        toxic or flammable leak is detected.    -   for the ventilation above the cylinders being emptied or        analyzed, under normal operating conditions a ventilation flow        rate of 100 Nm³/h for each cylinder is applied with, on the        whole, 1600 Nm³/h if a toxic or flammable leak is detected.

The raw materials used for producing these mixtures, which may beflammable and/or toxic gases, are positioned in sources connected to theequipment 4, 13, 12 of the plant 1 from the outside. This saves space inthe ISO container 10 and makes it easier to manage the risks of ignitionand explosion in the event of leaks of flammable gas from the cylinders.

This plant 1 is capable of producing mixtures of special gases requiredby the key users: refineries, petrochemical plants, the automotiveindustry and research laboratories for example.

Said plant according to the invention can also advantageously be used asa plant for conducting tests on limited numbers of cylinders and ifthese tests prove conclusive, a decision may be made to install a largersized plant in order to increase production.

By way of example, here are some non-exhaustive lists of mixtures ofspecial gases that can be produced by the plant according to theinvention.

Examples of Mixtures for Analysis Apparatus:

5% or 10% of CH₄ in argon 2% or 5% of H₂ in argon 40% of H₂ in helium10% of CO₂ in argon 5% of CO₂ in oxygen 5% of CO₂/5% or 10% of H₂ innitrogen 10% of CO₂/10% of H₂ in nitrogen 40% or 45% of H₂ in nitrogen

Examples of Mixtures for Measuring Atmospheric Pollution:

Composition Concentration NH₃ in N₂ 15 ppm HCl in N₂ 10 to 45 ppm CO inN₂ 45 to 9000 ppm H₂S in N₂ 5 to 1000 ppm NO in N₂ 8 to 1800 ppm C₃H₈ inair 3 to 3000 ppm CO in air 9 to 15 ppm NO₂ in air 9 to 450 ppm SO₂ inair 28 to 500 ppm NO/NO_(x) in N₂ 40 to 1000 ppm

Examples of Hydrocarbon Mixtures Used in Refinery and PetrochemicalPlants:

Mixtures of gaseous hydrocarbons (2 to 10 components) Mixtures of liquidhydrocarbons (2 to 10 components)

1-12. (canceled)
 13. A plant for filling cylinders with gas using puregases and/or mixtures of pure gases or of special gases, comprising: a)equipment capable of selecting gases and/or of producing mixtures ofgases intended to be introduced into a gas cylinder, and b) an apparatuscapable of analyzing the composition of said mixtures or of said puregases; wherein the plant is wholly contained in a transportablecontainer, the footprint of which is less than 45 m²; wherein theequipment and the apparatus are attached to a wall of the transportablecontainer; wherein the transportable container is configured to permitthe equipment and the apparatus to be connected to gas sources situatedoutside the container; and wherein the equipment and the apparatus areconfigured within the transportable container such that personnel arecapable of accessing and operating the equipment and the apparatus frominside the transportable container to fill cylinders.
 14. The plant ofclaim 13, comprising two parts: i) a first part comprising: equipmentconfigured to produce mixtures of pure gases or of special gases, andthe apparatus capable of analyzing the composition of said mixtures ofspecial gases or pure gases, j) the second part comprising: at least oneemptying device adapted to empty out residual gases contained incylinders that are to be filled, at least one device adapted to cleanand/or of passivate the cylinders that are to be filled, at least onedevice capable of homogenizing the mixtures of pure gases or of specialgases.
 15. The plant of claim 14, wherein the two parts are separatedfrom one another by a movable wall.
 16. The plant of claim 14, whereinsaid first part further comprises an apparatus adapted to control theinterior temperature.
 17. The plant of claim 13, wherein the equipmentconfigured to produce mixtures of pure gases or of special gasescomprises at least one mixer associated with at least one analyzer. 18.The plant of claim 13, wherein the equipment configured to producemixtures of pure gases or of special gases comprises: a weighingapparatus and/or manometric apparatus each able to measure accuratelythe quantities of gas to be introduced into said cylinder, and a fluidconnection between the cylinder that is to be filled and gas sourcessituated outside the container.
 19. The plant of claim 18, wherein theequipment configured to produce mixtures of pure gases or of specialgases comprises at least one line set able to produce any type ofcompressed or liquid gas mixtures.
 20. The plant of claim 18, whereinthe weighing apparatus situated in the transportable container ispositioned on a support which is independent of the container, thesupport having a base situated below the container floor level.
 21. Theplant of claim 13, wherein it comprises at least one apparatus capableof analyzing the composition of said mixtures or of said pure gases,chosen from: at least one gas chromatograph; a thermal conductivitydetector (TCD); a flame ionization detector (FID); an oxygen analyzer; amoisture analyzer; or an infrared spectrometer.
 22. The method ofpreparing a mixture of special gases in a cylinder implementing a plantas defined in claim 14 connected to at least two sources of specialgases external to the plant comprising the steps: preparing the cylinderthat is to be filled; using a weighing apparatus and/or manometricapparatus each able to measure accurately the quantities of gas to beintroduced into said cylinder; filling said cylinder by connecting it toa source of gas, and analyzing the composition of the content of thecylinder thus filled.
 23. The method of claim 22, wherein the cylinderthat is to be filled is connected to just one gas source at a time.